The present invention relates to a cast housing, and in particular to a cast housing of a transmission with an improved fluid path for lubricating a bearing.
A conventional transmission can include an outer cast housing that encloses gears, shafts, clutches, friction/reaction plates, variators, planetary gear sets, bearings, etc. The outer cast housing can be formed by a plurality of housings connected to one another. During operation, the internal components of the transmission can reach extreme temperatures and therefore require a means for cooling. A bearing, for example, requires a lubricant to be applied or sprayed into contact therewith in order to maintain the temperature of the bearing below a certain threshold. Once the bearing temperature exceeds the threshold, the bearing can fail causing potential damage to the transmission and negatively affecting its operation.
There are several conventional ways in which a bearing or other internal component is lubricated. One such way, for example, is to apply lubrication to the bearing before it is installed or assembled in the transmission. However, over a period of time the bearing needs additional lubrication, particularly if the bearing temperature reaches an extreme temperature. Therefore, a conventional transmission can include a plurality of lube circuits integrated therein. A pump can supply a lubricant to a plurality of lube circuits in the transmission. For example, a shaft can be drilled with lube holes to allow a lubricant to pass therethrough and provide sufficient lubrication to bearings and other internal components.
The lubricant can be a transmission fluid such as TranSynd™, which is a synthetic oil formulated by Castrol Ltd. One skilled in the art may know of other types of lubricants. During operation, the amount of torque and power generated by a transmission can put a significant amount of stress on a shaft in the transmission. This stress can limit the quantity and location of lube circuits formed in the shaft. In such instances, a bearing that would ordinarily be lubricated by a lubricant passing through a lube hole in the shaft may be lubricated in an alternative manner. Often times, the bearing may not receive enough lubrication and eventually fail, or the transmission may need to be redesigned such that more lubricant reaches the bearing. Alternatively, the bearing may need to be relocated inside the transmission where a nearby lube circuit is provided. In other designs, lubricant is directed through lube circuits which indirectly supply lubrication to the bearing. Again, the bearing may not receive enough lubrication and eventually overheat and/or fail.
Therefore, a need exists for a cast housing with an improved lube path integrated therein for providing sufficient lube to a bearing enclosed within the housing, particularly when a lube path cannot be integrally formed in a shaft.